Both motors on the z axis rotates sometimes only one

I need your help. At first I replace the bushing IGUs that has been damaged and cause one axis in the z axis only moves one of the right side only, or switch to the left, apparently after replacing the result is still the same.

I decided to take off the motor on the z axis of the rails of the x-axis and 2 smooth rod. Then I use this G1 Z50 F2000 and homing, it turns out the two motors on the z axis rotates either the right or left, the part that stops just vibrate and make a sound, and sometimes the two motors that spin as usual, I tried to give the lubricant and the result was still the same ,